Posted
by
samzenpus
on Tuesday November 01, 2011 @11:49AM
from the you-want-me-to-fly-in-what-now? dept.

garymortimer writes "A German team has managed to fly its super-sized hobby inspired platform with a man on-board! A one-hour flight would cost something near to 6 Euro for electricity. In addition, the device holds few parts that could wear out, making maintenance intervals and cost low and far between. The control firmware can be integrated with a sophisticated integrated GPS system or obstacle detection. As such, automated flight for predetermined points on a 3D map is possible."

Plans would instantly kill people. While R/C is an amazing hobby, you have to know a few things. These blades are not protected, that guy wearing a helmet? It's not going to help him when a blade breaks and decapitates him! and while motor failure was discussed, an unballanced rotor wasn't... That will screw things up fast!

I'd fly one in a heartbeat, assuming I had the skill, of course...I'm (so far) strictly a fixed-wing pilot:-)

First, I seriously doubt one of those blades would even remotely decapitate the pilot. As I've already discussed in the comments to this article [slashdot.org], I think the likelihood of a blade breaking is very, very remote. Even if a blade were to fail, did you see the size of those blades? I doubt they would have the mass to penetrate deeply even if a blade broke and even if it were to fail in such a way

At about 0:44 in the video included in TFA, you can see them starting to load out the batteries. There appears to be one battery pack per motor, which eliminates the possibility of centralized battery failure. Can't say if there are redundancies in the control mechanisms.

This is most certainly a proof-of-concept prototype. Adding more robust safety and control systems should happen after they prove the thing works, which it appears they have.

Autorotation requires variable-pitch rotors; these are fixed pitch, but with some redundancy in the power and control systems, I bet this thing can be made rather safe. They look like large off-the-shelf model airplane props. A bit scary when they all spin like that, but a shroud around the prop can catch any debris if a prop breaks, and the control system can quickly shut that motor down.

Oh, and these multirotor platforms are easy to stabilise; with the right control system this thing will be a snap t

That would make it more stable, but harder to maneuver. With the center of mass in the plane of the rotors, it only takes very slight modifications to the torque to rotate it, and is probably the more power efficient way to do it. There is much more micromanaging of the controls to keep it level this way, but this is all done by computer and the pilot is fucked in any case if the computer fails.

It has been a while since I was obsessing over this stuff as a kid, but I believe that was one of the innovatio

You don't put the CM right in the plane of the rotors. That's the critically stable point. You put it a few cm or dm below that. Now you have stability, and only a small moment to overcome to hold a non-level attitude. But, if you suspend the pilot below the frame, and gimbal the strut he's hanging from, now you're not worried about that moment at all. Make the gimbal an actively controlled joint, and you can use it for control, too. I call prior art.

I did not mean precisely at the critical point, just that the entire body of the pilot should not be dramatically displaced. I still think that the critically stable point is a reasonable goal, considering that the computer can continually adjust the individual motors to keep the thing upright, and there is no gravitational torque to continually fight for any ground speed. A free gimbal would demand that the motors be powerful enough to correct for chaotic forces from a swinging 100KG mass in addition to

That bulb under the pilot is a Swiss Ball [google.com], and it's there because it's cheap, light, tough, and pretty foolproof as a landing gear for a hovering vehicle.

The best reason to depress the CM below the rotors is that you don't have to do so much fine control to get what you want. You won't get terrific responsiveness, but you won't be wobbling about a nearly-unstable balance point.

If they do that, though, it stops being really different and becomes similar to any other lightweight helicopter, only with 8 small

20-50kW of power is going to cost you a lot more than six euros. 200A two phase run from the nearby transformer, plus a breaker and distribution panel wired to code, is going to cost you a couple thousand. Car batteries are good for 6-8kW each, so you could probably get by with 300-500 euros that route. A smallish capacitor bank would likely be the cheapest route to that much power, but isn't going to last long.

Now at US electricity rates, you're looking at around €0.06/kWh. I've heard European rat

I agree with all you are saying:) In fact that's what I was pointing that the grid itself cannot provide that much charging power over a conventional 13amp wire (what we use in the UK) and even a 60amp wire (approx 6 to 7 KW) is going to still take a long time to charge.

It is "possible" to get 20 to 50 KWH in six euros, let me explain.

Here in the UK, we dont have standing (compulsory) charges, instead they charge the first few KWH at a higher rate than the normal rate. so for example, the first 3 KWH is 25

Kilowatt hours (kWh) is a measure of energy, and costs however much your local power utility charges you. I did say that €6 did sound like a reasonable utility charge for 20-50kWh of energy. However, you did not say kWh, you said kW, a measure of instantaneous power. Not only that but you specifically said it was power and not energy.

The cost of instantaneous power is the cost of whatever device you use to provide that power. That could be a bank of capacitors, a bank of batteries, an engine ho

No, it'd be more efficient to get rid of the electric motor altogether, and have a piston or turbine engine driving the rotors directly. Of course, that's exactly what modern helicopters do.

You won't get any efficiency benefits by creating electricity with a generator and driving an electric motor with it. That only works in cars, where the load is highly variable, and in trains and construction equipment, where they need the gigantic stall torque that electric motors can create; in both situations, weigh

No, it's not. On a helicopter, there's only two rotors, and they're mechanically linked together because there's no reason to spin them at different speeds (you control them by altering the pitch of the blades). Even if there were a good reason for that, it still wouldn't come close to making up for the enormous weight penalty of a hybrid-electric system.

I've said it before the last time one of these dumb electric helicopter stories came up on Slashdot, and I'll say it again. Electric helicopters will NE

But this thing DOES carry a human! Granted, it's not carrying him any distance, but it at least got off the ground. One order of magnitude in battery performance improvement would make this device workable for some applications. Of course, the last order of magnitude improvement took 50 years, so I'm not holding my breath.

No, it's not. On a helicopter, there's only two rotors, and they're mechanically linked together because there's no reason to spin them at different speeds (you control them by altering the pitch of the blades).

Exactly this is not necessary with these Brushless E-Engines.
The control is done by some gyros and electronics. No complex pitch control as in helicopters. No horrible mechanics, required to be maintained every day.
No redundant hydraulic systems, no prove that the system remains halfway stable and controllable by a (extremely experienced) pilot, if the
single (turbine) engine breaks and you have to autogyro.
This prototype is already able to fly up to 20mins with the current LIPO batteries. It stabilizes

Doesn't work with these multicopter setups. They do not run at 100% all the time since the blades are fixed pitch. Direction and stability is maintained by varying the speed and each rotor has to be independent of the others. You'd need a massively complex mechanical setup to achieve that.

To do what you are saying, you'd require variable pitch blades so the engine could run at 100% all the time.

At 20c per KWH, $8 would be 40 KWH of electricity. I think I actually pay more like 10c, but never mind. Using lead-acid batteries to produce 40 KWH of electricity would require (... quickly delving into Wikipedia [wikipedia.org]...) about 1000 lbs. of batteries, assuming you could pull ALL the electricity out, which you can't - more like 30%. So, 3000 lbs. of batteries.

OTOH, a smallish car engine would do fine. Funny how that works.

That thing looks like the original saucer-shaped predecessor of the Moller SkyCar migh [wikipedia.org]

Yep. I was too lazy to look up Li-ion battery data as well. If they are 3X better, then it's still 1000 lbs. of batteries. And looking back at my arithmetic, I may have swapped Kg for lb., which makes things 2.2 times worse. Let's see - lead-acid = 40 WH / Kg. We need 40000 WH => 1000 Kg (not lb), and we can't use the whole amount, only 1/3 = 3000 Kg. So it is 2.2 times worse. You'll need 3000 Kg of lead-acid or 1000 Kg of Li-ion batteries. Sorry 'bout that.:P

My friend lost power in a storm a few months ago, and I rigged up a male to male extension cord, and plugged my inverter into his wall outlet, and we backfed power into his house to keep a few things going. I was charging group 31 deep cycle batteries on my commute to work, and I measured that they held almost exactly 1 KwH of energy each. Depending on the type of charge it took anywhere from 1.3X to 2.0X to charge them.

It is definitely interesting trying to live on 1 - 2 KwH a day and keep stuff going. T

I know someone who lives off the grid, on 60 acres. He started out with a diesel generator until he got his house built, now he has solar and a bit of wind. He has a very nice power system. The system looks at the wire every second to see if there is any demand, and if there is it provide the full 2 or 3 KW. The rest of the time it doesn't waste its own power maintaining the level. He had a heck of a time tracking down all the stray hidden power drains - even an LED on some piece of equipment was enoug

In one hour flight I could do it twice or more the way from my house to work and back. That with the fact of being quiet and possibly take up less space than a car when saved creates an interesting way to replace a car

In one hour flight I could do it twice or more the way from my house to work and back. That with the fact of being quiet and possibly take up less space than a car when saved creates an interesting way to replace a car

Can you? Your scenario is exactly where I was going with it. The flying car is approaching us and all that. However, that's only assuming the thing moves fast enough that you could make it to work in back in a reasonable time. If we're talking about an hour's flight hovering around for fun, that's still incredibly cool in that it makes hobby flying more accessible to people, but it's not going to change the world.

First, let me say that I agree that the pilot should probably be under the blades, although I'm more concerned about stability. Lots of people have commented on the possibility of broken propellers, and yes, that is something to consider. However, I'd say it's less of a factor than most people on/. seem to think. I've got somewhere between 900 and 1000 hours of pilot in command time* in about 20 years and guess how many in-flight propeller failures I've seen in that time?

First, let me say that I agree that the pilot should probably be under the blades, although I'm more concerned about stability. Lots of people have commented on the possibility of broken propellers, and yes, that is something to consider. However, I'd say it's less of a factor than most people on/. seem to think. I've got somewhere between 900 and 1000 hours of pilot in command time* in about 20 years and guess how many in-flight propeller failures I've seen in that time?...
*admittedly, in airplanes, not helicopters and most definitely not multicopters. I'd be surprised if that made any difference, however.

As far as I understood, the pilot position is wanted above, because it allows to use a typical parachute safety, as in many ultralights.
This is impossible with normal helicopter setups, due to the rotor on top.
As for stability: without the electronic controller this beast will be inherently instable (doesn't matter where the COG is).
With the controller the neutral state is, that the thing balances itself, hovering on the spot. With some reasonable controller (GPS etc.) it
would even stabilize it's absol

I always wondered if this was possible. I thought the main problem would be sluggishness due to the increased mass of the props, but dividing the load among many smaller props helps to reduce this problem. But now it works! SWEET! And the increased number of props means better redundancy so more engines can fail without it dropping out of the sky.

Now it looks like they need more power. No need to be green at this stage, try hooking up a Rotax/micro-turbine generator to get some more juice and see how it goe

You know this needs to lift itself into the air right? It's not an airship, it's more like a small helicopter. It surely uses at least as much as an electric compact car would under heavy acceleration. The other problem is range. For now gasoline is still way more space & weight-efficient than any kind of battery at this scale.

Every time i see one of these amateur fly-by-wire setups, i think of the F-16 development. One of the main show stoppers in the F-16 was the fact that the software would get confused when crossing the equator. It would flip the plane upside down fast enough to kill the pilot and then happily fly upside down until it ran out of fuel. Other little things like it would allow for wheels up while sitting on the tarmac, or allowing a bomb to come off the rack while inverted. Automation in flying is hard, and quite honestly you have to be prepared to lose pilots.
http://catless.ncl.ac.uk/Risks/3.44.html [ncl.ac.uk]

The shuttle? The US space shuttle? Which couldn't be launched in late December because the computer couldn't cope with year end roll over? Because the programmers didn't think the shuttle would ever be in orbit over the New Year? Seriously? A problem that existed since Mercury, was repeated on the shuttle and wasn't fixed until 2007? That's your standard of excellence?

That's just silly, every single article you link to. The specs for the code were such that there would be no year-end-crossing missions, that's all there is to it. This has nothing to do with when was the flight software designed in. It simply wasn't in the specs back then, and there was no funding to change it any time earlier than when they did actually change the specs and implemented it. You're providing a straw man for an argument. Space Shuttle's flight software was probably the best engineered piece

This is not necessarily a mistake: one of the methods for low-level delivery of a nuclear bomb while still giving the airplane time to get out of the blast radius is to release the bomb while performing a tight Immelmann loop. This has the effect of throwing the bomb upwards, and unless you've got perfect timing on the bomb release, releases the bomb when the aircraft is partially inverted.

Rework the design so that instead of a pilot you have a circular ring in the center that can allow the craft to float over a prepared object (or person?) and, using some kind of servo, attach it to the craft to be delivered to a hard-to-reach area. With GPS the craft can auto-release at a designated location and height.

Be neat to auto-guide the craft to a location, deliver an object, then return to base for recharging. Then reverse the path to return the object (or person's new location?) back.

Was thinking more like live cargo, military or private, or medical supplies.

Private: Drop of a hiker somewhere normally inaccessible by foot, they wander around, then they get picked up at a prearranged time.

Military: Paratrooper or other grunt gets airlifted from boat, flies low to avoid radar, auto-ejected at a certain point, and craft returns. If clearing big enough then possible pickup of grunt/trooper possible as well.

Medical: Can lift off and drop off needed medical assistance that normally too heavy

Was thinking more like live cargo, military or private, or medical supplies.

None of this is any different from a current helicopter

Private: Drop of a hiker somewhere normally inaccessible by foot, they wander around, then they get picked up at a prearranged time.

Heliskiing

Military: Paratrooper or other grunt gets airlifted from boat, flies low to avoid radar, auto-ejected at a certain point, and craft returns. If clearing big enough then possible pickup of grunt/trooper possible as well.

This thing, with 16 motors introduces many more points of failure. Very cool, but practical? No. And definitely not useful for real world applications. Not yet, anyway.

Hmm: think again: A normal current helicopter with some hundred moving parts around the head- and the tail rotors under heavy load and wear should be better
than 16 moving parts running smoothly on ball bearings? The only critical part here is the flight control software, everything else is damn simple technology, compared to any existing heli design.
It also already contains redundancy, 4 out of 16 motors are allowed to fail...

Looks similar to a Great Planes 65cc 80-85-160 Brushless Outrunner Electric Motor [towerhobbies.com]. This particular motor is rated for 7500 W continuous, 8400 W surge. No, I didn't accidentally add a zero. Yes, approximately 10hp out of a motor that fits in a 3.5" cube. Outrunners are pretty damned amazing.

Note - to achieve this power level, you'll need to feed said motor with 125 amps at 30-50V. No small task there.

In the video this thing never got out of ground effect -- although it did hover high in its ground effect -- so it may be more of a GEM (ground effect machine, aka hovercraft with no skirt) than a helicopter. Still cool, but of more-limited utility.

The mounting system for the motors and props seemed a bit funky. It's not clear what's holding the props onto the shafts, and the motors are bolted to the top of the airframe. Instinctively I'd prefer things the other way around, so that the forces are trying

I wonder why they didn't mount one motor/rotor underneath one on top of the arm to minimize the footprint of the thing. DraganFlyer is doing that now.Then, why couldn't you use even bigger motors and bigger props or are these the biggest brushless motors available? Or is it a question of rotor/armature mass that would slow down the response rate of speed changes.